Magnetic driving implement with cupshaped magnetic portion for greater holding strength



May 16, G. CL RK MAGNETIC DRIVING IMPLEMENT WITH CUP-SHAPED MAGNETIC PORTION FOR GREATER HOLDING STRENGTH Filed Jan. 21, 1965 I N VEN TOR.

BWJW 7 ATTORNEYS.

United States Patent 3,320,563 MAGNETIC DRIVING IMPLEMENT WITH CUP- SHAPED -MAGNETIC PORTION FOR GREATER HOLDING STRENGTH Frederick G. Clark, Buffalo, N.Y., assignor of one-half to Wade Stevenson, Buffalo, N.Y. Filed Jan. 21, 1965, Ser. No. 426,934 1 Claim. (Cl. 335-285) This invention relates to magnetic driving implements for holding magnetic articles in a socket formed on the end of a rotatable shank.

One of the objects of this invention is to provide an implement of this type in which it is so constructed that the magnet is enabled to exert greater holding power on the articles so that they may be securely held in the implement.

Another object is to provide the implement with a cupshaped member of material of high magnetic permeability, such as soft iron, for forming a substantially complete magnetic circuit through the article and both poles of the magnet.

In the accompanying drawing:

FIG. 1 is a longitudinal, sectional view of the lower part of a shank of a magnetic driving implement having a socket formed in the end thereof for receiving articles, and showing a bolt held in the socket.

FIG. 2 is a bottom plan view thereof.

FIG. 3 is a fragmentary, central sectional view thereof on an enlarged scale.

In prior constructions for similar purposes a bar magnet was installed in the socket of an implement with one end thereof in position to engage the article to be held in the socket. This construction provided one or more air gaps through which the magnetic lines of force had to pass, with the result that the magnetic force acting on the article was considerably reduced. It is of course quite important that the articles be gripped firmly in the sockets, especially where a number or bolts or nuts are placed in the sockets of multiple spindle drive tools, for assembling a number of fasteners in a single operation, since if the workpieces are not held securely they may fall out of the sockets and interfere with the assembled mechanism, or one of them may tilt slightly in its socket and may strip the threads on the receiving part.

In accordance with my present invention a substantially continuous path for the magnetic lines of force through a magnetic circuit of low reluctance is provided with the minimum amount of an air gap in this circuit.

In the particular embodiment of this invention illustrated by way of example in the drawings, 5 represents a portion of the shank of a socket wrench which is preferably, at least in part, of a hollow, tubular, cylindrical form, and the outer end of the shank is provided with a hollow, tubular socket 6. The other end of the shank may be provided with suitable means for turning the same about its axis, either manually or by a power-operated mechanism. The outer endof the socket has an interior surface of non-circular form into which an article to be turned, such as a nut or head of a screw or bolt 7 may extend so as to be rotated when the shank is rotated about its axis.

8 represents a permanent magnet which in the construction shown is of the bar type having opposite poles thereof at the opposite ends of the magnet. This magnet may be of any suitable cross sectional shape, for example, circular, as in the construction illustrated, and is positioned in the socket so that the lower face thereof may contact with the article 7 to hold the same in the socket.

The magnet is enclosed on its peripheral portion by means of a sleeve 10 of a non-magnetic material and the magnet together with the sleeve 10 is arranged in an in- 3,320,563 Patented May 16, 1967 verted cup-shaped member 12 of which readily conducts magnetic linesof force, such for example as soft iron. This cup-shaped member, in addition to its cylindrical sides 14, has a transversely extending head or end wall 16 which may be formed integral with the cylindrical wall as shown, and which may be a separate piece or disk also made of a material which readily conducts lines of force. This disk may be secured to the inner end of the cylindrical wall or merely placed in contact with this end of the cylindrical wall in which case it will be drawn into contact with the cylindrical wall by magnetic force.

The open end of this cup-shaped member is arranged so that it will also contact with the implement to be held in the socket. For example, in the construction in which the article 7 has a fiat head, the open end of the cup-shaped member 12 is substantially coplanar with the outer end of the magnet 8 so that both the end of the magnet 8 and the open end of the cup-shaped member 12 will contact with the article, thus forming a magnet end of the cup-shaped member, back to the magnet, thus formmg a substantially complete magnetic circuit substantially free from air gaps. This permits the magnet to hold the articles very firmly in the socket 6 where the articles to be held have curved or rounded ends, the outer end of the cup 12 may extend downwardly from the position shown in the drawing into contact or close proximity to the head of the article.

Preferably I also provide another sleeve 18 of nonmagnetic material about the outer surface of the cupshaped member so as to insulate this member magnetically from the shank 5. It Will be understood of course that if the shank 5 is made of a non-magnetic material this sleeve 18 will not be necessary.

In assembling my magnetic driving implement, the magnet and sleeve 10 are pressed into the cup-member the open end of the cup 12 facing the workpiece recess in the socket.

It will be understood that various changes in the details, materials and arrangements of parts which have been herein described and illustrated in order to explain the nature of the invention maybe made by those skilled in the art Within the principle and scope of the invention as expressed in the appended claim.

What is claimed is:

A rotatable shank for a magnetic driving implement for holding articles of magnetic material, said shank including:

(a) a socket formed in the outer end of said shank to receive an article;

(b) said shank having a tubular centrally disposed bore immediately above said socket and having substantial-ly the same cross sectional area;

(c) a sleeve of non-magnetic material tightly fitted into said tubular bore;

(d) a cup-shaped member of magnetic material having high magnetic conductivity tightly fitted within said non-magnetic sleeve open face down and having its upwardly disposed end wall adjacent to the upper end of said bore;

(e) an inner sleeve of non-magnetic material tightly fitted within said cup-shaped member;

(f) a bar type magnet having poles at opposite ends thereof tightly fitted Within said non-magnetic inner sleeve and having an upper pole in engagement with the said end wall of the cup-shaped member, said a magnetic material 3,320,563 3 4 cup-shaped member thereby providing an annular circuit path which radiates outwardly from the said high flux density path from said magnet upper pole; lower pole of said magnet. and (g) said open face of said cup-shaped member and References Clted by the Exammer the lower pole of said magnet both terminating adja- 5 UNITED STATES PATENTS cent to said socket to engage an article inserted there- 2 718,306 9 /'195 5 Cl k 81 12.5 in whereby an exposed annular open end magnetic 2,782,822, 2/1957 Cla k 81-125 X circuit of substantially the same area as the article U to be held is presented and nearly all of the top BRNARD GILHEANY Pnmary Examiner surface of the article becomes part of the magnetic 10 H. A. LEWITTER, Assistant Examiner. 

